Memory system with a zoned namespace and an operating method thereof

A memory system, comprising:

• at least one memory die including plural memory blocks, each memory block including plural memory cells capable of one or more bit data;
• and
• a controller configured to establish at least one first open zone in response to a command input from an external device and at least one second open zone without the command input from the external device, receive plural write requests associated with the at least one first open zone, each write request input along with a program data from the external device, and perform a program operation corresponding to a write request among the plural write requests in a first memory block allocated for the at least one second open zone while performing a program operation corresponding to another write request among the plural write request in a second memory block allocated form the at least one first open zone,
• wherein the controller performs the program operation corresponding to the write request in an order of the plural write requests in the second memory block and the program operation corresponding to the write request in a reverse order of the plural write requests in the first memory block.